Stent anchoring system

ABSTRACT

An illustrative stent may comprise an elongated tubular member having a first end and a second end and an intermediate region disposed therebetween. The elongated tubular member may include at least one barb attached thereto. The barb may be configured to be tucked under a filament of the stent during delivery of the stent and protrude radially from the stent, when the stent is deployed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to U.S.Provisional Application Ser. No. 62/419,810, filed Nov. 9, 2016, theentirety of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure pertains to medical devices, methods formanufacturing medical devices, and uses thereof. More particularly, thepresent disclosure pertains to an anti-migration stent for implantationin a body lumen, and associated methods.

BACKGROUND

Implantable stents are devices that are placed in a body lumen, such asthe esophageal tract, the gastrointestinal tract (including theintestine, stomach and the colon), tracheobronchial tract, urinarytract, biliary tract, vascular system, etc. to provide support and tomaintain the body lumen open. These stents are manufactured by any oneof a variety of different manufacturing methods and may be usedaccording to any one of a variety of methods. Of the known stents,delivery systems, and methods, each has certain advantages anddisadvantages. For example, in some stents, the compressible andflexible properties that assist in stent delivery may also result in astent that has a tendency to migrate from its originally deployedposition. For example, stents that are designed to be positioned in theesophageal or gastrointestinal tract may have a tendency to migrate dueto peristalsis (i.e., the involuntary constriction and relaxation of themuscles of the esophagus, intestine, and colon which push the contentsof the canal therethrough). Thus, there is an ongoing need to providealternative stents having anti-migration features and associateddelivery systems as well as alternative methods for manufacturing andusing stents having anti-migration features and associated deliverysystems.

BRIEF SUMMARY

This disclosure provides design, material, manufacturing method, and usealternatives for medical devices. An example medical device may includea stent.

One illustrative example is a stent including an elongated tubularmember comprising at least one interwoven filament defining a pluralityof cells. The elongated tubular member is configured to move between acollapsed configuration and an expanded configuration. In the collapsedconfiguration, the plurality of cells have a first profile and in theexpanded configuration the plurality of cells have a second profiledifferent from the first profile. The stent also includes at least onebarb attached to the at least one filament at one end of the barb andextending towards a free end. The free end of the at least one barb isconfigured to be positioned radially inward to an adjacent winding ofthe at least one interwoven filament when the elongated tubular memberis in the collapsed configuration and to extend radially outward fromthe elongated tubular member when the elongated tubular member is in theexpanded configuration.

Additionally or alternatively to any example above, the first profile ofthe plurality of cells has a major dimension extending along alongitudinal axis of the elongated tubular member.

Additionally or alternatively to any example above, the second profileof the plurality of cells has a major dimension extending along acircumference of the elongated tubular member.

Additionally or alternatively to any example above, the at least onebarb comprises a wire.

Additionally or alternatively to any example above, the at least onebarb is attached to the at least one filament at a terminal end of theat least one barb.

Additionally or alternatively to any example above, the at least onebarb is attached to the at least one filament along a length of the atleast one barb, the length extending from a terminal end to a pointproximal to the free end.

Additionally or alternatively to any example above, the at least onebarb is attached to the at least one filament at a first end of the atleast one barb and a second end of the at least one barb, wherein thefree end of the at least one barb is a region intermediate to the firstend and the second end.

Additionally or alternatively to any example above, the at least onebarb has a generally triangular shape.

Additionally or alternatively to any example above, the at least onebarb comprises a wire helically wound around the at least one filament.

Additionally or alternatively to any example above, the at least onebarb is biased to extend radially outward from the elongated tubularmember when unconstrained.

Additionally or alternatively to any example above, the at least onebarb comprises a material combination which behaves like a temperaturesensitive bimetallic strip.

Additionally or alternatively to any example above, the at least onebarb comprises a plurality of barbs spaced along a length and acircumference of the elongated tubular member.

Additionally or alternatively to any example above, the at least onebarb comprises a plurality of barbs, wherein at least some of theplurality of barbs have a first length and at least some of theplurality of barbs have a second length different from the first length.

Additionally or alternatively to any example above, the at least onebarb comprises two or more wires fixed at a same location on the atleast one filament.

Additionally or alternatively to any example above, when in thecollapsed configuration the adjacent winding is configured to exert aradially inward force on the at least one barb.

Another example is a stent including an elongated tubular membercomprising at least one filament wound to form a plurality of cells. Theelongated tubular member is configured to move between a collapsedconfiguration and an expanded configuration. The stent also includes aplurality of barbs affixed to the at least one filament and comprising ashape memory wire. The plurality of barbs are biased to extend radiallyoutward from the elongated tubular member when unconstrained. In thecollapsed configuration, the ate least one filament applies a radiallyinward constraining force to a free end of each barb of the plurality ofbarbs such that the free ends are constrained radially inward of the atleast one filament, and as the elongated tubular member moves from thecollapsed configuration to the expanded configuration the free end of atleast some of the plurality of barbs is unconstrained by the at leastone filament and extends radially outward from the elongated tubularmember.

Additionally or alternatively to any example above, at least some of theplurality of barbs have a first length and at least some of theplurality of barbs have a second length greater than the first length.

Additionally or alternatively to any example above, the constrainingforce is removed from the barbs having the first length before the barbshaving the second length.

Yet another example is a stent including an elongated tubular membercomprising at least one filament wound to form a plurality of cells. Theelongated tubular member is configured to move between a collapsedconfiguration and an expanded configuration. In the collapsedconfiguration, the plurality of cells have a first profile and in theexpanded configuration the plurality of cells have a second profiledifferent from the first profile. The stent also includes at least onebarb attached to the at least one filament at one end of the barb andextending towards a free end. The first profile is configured to exert aconstraining force on the at least one barb to position the at least onebarb radially inward of the at least one filament and the second profileis configured to remove the constraining force from the at least onebarb such that the free end of the at least one barb extends radiallyoutward from the elongated tubular member.

Additionally or alternatively to any example above, the at least onebarb comprises a shape memory material.

Additionally or alternatively to any example above, when the free end ofthe at least one barb extends radially outward from the elongatedtubular member, the at least one barb is at an angle of in the range of2° to 90° relative to a longitudinal axis of the elongated tubularmember.

The above summary of some embodiments is not intended to describe eachdisclosed embodiment or every implementation of the present disclosure.The Figures, and Detailed Description, which follow, more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments in connection withthe accompanying drawings, in which:

FIG. 1 is a side view of an illustrative stent having an anti-migrationanchoring system.

FIG. 2 is a partial side view of an illustrative stent anchoring systemin a collapsed configuration.

FIG. 3 is a partial side view of the illustrative stent anchoring systemof FIG. 2 in a partially deployed configuration.

FIG. 4 is a partial side view of the illustrative stent anchoring systemof FIGS. 2 and 3 in a fully deployed configuration.

FIG. 5 is a perspective view of another illustrative stent anchoringsystem.

FIG. 6 is a side view of a portion of another illustrative stentanchoring system in a first configuration.

FIG. 7 is a side view of a portion of the illustrative stent anchoringsystem of FIG. 6 in a second configuration.

FIG. 8 is a side view of a portion of another illustrative stentanchoring system in a first configuration.

FIG. 9 is a side view of a portion of the illustrative stent anchoringsystem of FIG. 8 in a second configuration.

FIG. 10 is a perspective view of a portion of an illustrative stentincluding an anchoring system in a first configuration.

FIG. 10A is a cross-sectional view of a portion of the stent of FIG. 10including the anchoring system in the first configuration.

FIG. 11 is a perspective view of a portion of the illustrative stent ofFIG. 10 including the anchoring system in a second configuration.

FIG. 11A is a cross-sectional view of a portion of the stent of FIG. 11including the anchoring system in the second configuration.

While the disclosure is amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit aspects of theinvention to the particular embodiments described. On the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the scope of the invention.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

Although some suitable dimensions ranges and/or values pertaining tovarious components, features and/or specifications are disclosed, one ofskill in the art, incited by the present disclosure, would understanddesired dimensions, ranges and/or values may deviate from thoseexpressly disclosed.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the invention. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

In some instances, it may be desirable to provide an endoluminalimplant, or stent, that can deliver luminal patency in a patient with anesophageal stricture or other medical condition. Such stents may be usedin patients experiencing dysphagia, sometimes due to esophageal cancer.An esophageal stent may allow a patient to maintain nutrition via oralintake during cancer treatment or palliation periods. However, a commoncomplication of gastrointestinal (GI) stents is stent migration due tothe peristaltic motion subjected to the stent. It may be desirable toprovide a stent that can deliver luminal patency while minimizingmigration of the stent. While the embodiments disclosed herein arediscussed with reference to esophageal stents, it is contemplated thatthe stents described herein may be used and sized for use in otherlocations such as, but not limited to: bodily tissue, bodily organs,vascular lumens, non-vascular lumens and combinations thereof, such as,but not limited to, in the coronary or peripheral vasculature, trachea,bronchi, colon, small intestine, biliary tract, urinary tract, prostate,brain, stomach and the like.

FIG. 1 illustrates a side view of an illustrative endoluminal implant10, such as, but not limited to, a stent. In some instances, the stent10 may be formed from an elongated tubular member 12. While the stent 10is described as generally tubular, it is contemplated that the stent 10may take any cross-sectional shape desired. The stent 10 may have afirst, or proximal end 14, a second, or distal end 16, and anintermediate region 18 disposed between the first end 14 and the secondend 16. The stent 10 may include a lumen 32 extending from a firstopening adjacent the first end 14 to a second opening adjacent to thesecond end 16 to allow for the passage of food, fluids, etc.

The stent 10 may be expandable from a first radially collapsedconfiguration (not explicitly shown) to a second radially expandedconfiguration. In some cases, the stent 10 may be deployed to aconfiguration between the collapsed configuration and a fully expandedconfiguration. The stent 10 may be structured to extend across astricture and to apply a radially outward pressure to the stricture in alumen to open the lumen and allow for the passage of foods, fluids, air,etc.

The proximal end 14 of the stent 10 may include a plurality of loops 38.The loops 38 may be configured to receive a retrieval tether or suture40 interwoven therethrough, or otherwise passing through one or more ofthe loops 38. The retrieval suture 40 may be used to collapse andretrieve the stent 10, if so desired. For example, the retrieval suture40 may be pulled like a drawstring to radially collapse the proximal end14 of the stent 10 to facilitate removal of the stent 10 from a bodylumen.

The stent 10 may have a woven structure, fabricated from a number offilaments or struts 36. In some embodiments, the stent 10 may be knittedor braided with a single filament interwoven with itself and definingopen cells. In other embodiments, the stent 10 may be braided withseveral filaments interwoven together and define open cells. Someexemplary stents including braided filaments include the WallFlex®,WALLSTENT®, and Polyflex® stents, made and distributed by BostonScientific, Corporation. In another embodiment, the stent 10 may beknitted, such as the Ultraflex™ stents made by Boston Scientific,Corporation. In yet another embodiment, the stent 10 may be of a knottedtype, such the Precision Colonic™ stents made by Boston Scientific,Corporation. In still another embodiment, the stent 10 may be a lasercut tubular member, such as the EPIC™ stents made by Boston Scientific,Corporation. A laser cut tubular member may have an open and/or closedcell geometry including one or more interconnected filaments or strutsdefining open cells therebetween. In some instances, an inner and/orouter surface of the stent 10 may be entirely, substantially orpartially, covered with a polymeric covering or coating. The covering orcoating may extend across and/or occlude one or more, or a plurality ofthe cells defined by the struts or filaments 36. The covering or coatingmay help reduce food impaction and/or tumor or tissue ingrowth. In somecases, the stent 10 may be a self-expanding stent (SES), although thisis not required.

In some instances, in the radially expanded configuration, the stent 10may include a first end region 20 proximate the proximal end 14 and asecond end region 22 proximate the second end 16. In some embodiments,the first end region 20 and the second end region 22 may includeretention features or anti-migration flared regions 24, 26 havingenlarged diameters relative to the intermediate portion 18. Theanti-migration flared regions 24, 26, which may be positioned adjacentto the first end 14 and the second end 16 of the stent 10, may beconfigured to engage an interior portion of the walls of the esophagusor other body lumen. In some embodiments, the retention features, orflared regions 24, 26 may have a larger diameter than the cylindricalintermediate region 18 of the stent 10 to prevent the stent 10 frommigrating once placed in the esophagus or other body lumen. It iscontemplated that the transition 28, 30 from the cross-sectional area ofthe intermediate region 18 to the retention features or flared regions24, 26 may be gradual, sloped, or occur in an abrupt step-wise manner,as desired.

In some embodiments, the first anti-migration flared region 24 may havea first outer diameter and the second anti-migration flared region 26may have a second outer diameter. In some instances, the first andsecond outer diameters may be approximately the same, while in otherinstances, the first and second outer diameters may be different. Insome embodiments, the stent 10 may include only one or none of theanti-migration flared regions 24, 26. For example, the first end region20 may include an anti-migration flare 24 while the second end region 22may have an outer diameter similar to the intermediate region 18. It isfurther contemplated that the second end region 22 may include ananti-migration flare 26 while the first end region 20 may have an outerdiameter similar to an outer diameter of the intermediate region 18. Insome embodiments, the stent 10 may have a uniform outer diameter fromthe first end 14 to the second end 16. In some embodiments, the outerdiameter of the intermediate region 18 may be in the range of 15 to 25millimeters. The outer diameter of the anti-migration flares 24, 26 maybe in the range of 20 to 30 millimeters. It is contemplated that theouter diameter of the stent 10 may be varied to suit the desiredapplication.

It is contemplated that the stent 10 can be made from a number ofdifferent materials such as, but not limited to, metals, metal alloys,shape memory alloys and/or polymers, as desired, enabling the stent 10to be expanded into shape when accurately positioned within the body. Insome instances, the material may be selected to enable the stent 10 tobe removed with relative ease as well. For example, the stent 10 can beformed from alloys such as, but not limited to, nitinol and Elgiloy®.Depending the on material selected for construction, the stent 10 may beself-expanding or require an external force to expand the stent 10. Insome embodiments, composite filaments may be used to make the stent 10,which may include, for example, an outer shell or cladding made ofnitinol and a core formed of platinum or other radiopaque material. Itis further contemplated the stent 10 may be formed from polymersincluding, but not limited to, polyethylene terephthalate (PET). In someinstances, the filaments of the stent 10, or portions thereof, may bebioabsorbable or biodegradable, while in other instances the filamentsof the stent 10, or portions thereof, may be biostable.

The stent 10 may further include one or more anti-migration or retentionfeatures, such as barbs 34 (e.g., tines, quills, etc.) attached to oneor more of the filaments 36. The barbs 34 may be configured to extendradially outward from an outer surface (and/or a longitudinal axis 42)of the stent body 12 to engage bodily tissue. In some cases, the barbs34 may be filament-like or wire-like structures. It is contemplated thata single wire or a group (e.g., two or more) of wires may form a barb34. In some cases, the barbs 34 may comprise a plate-like structure. Insome instances, the barbs 34 may be a unitary portion of the filaments.The barbs 34 may have a pointed or tapered free end to facilitateengagement into the tissue. The stent 10 may include any number of barbs34 desired such as, but not limited to, one or more, five or more, 20 ormore, 50 or more, 100 or more, etc.

The barbs 34 may be biased to extend radially outward from thelongitudinal axis 42 of the stent 10, when the stent 10 is in theexpanded configuration and the barbs 34 are unconstrained. For example,when the stent 10 is delivered at the desired location, the barbs 34 mayextend out from the filaments 36 (e.g., away from the longitudinal axis42 of the stent 10) at a desired angle and interact with (e.g.,penetrate) the surrounding anatomy to anchor the stent 10 and aid inanti-migration of the stent 10. It is contemplated that the angle of thebarbs 34 relative to the longitudinal axis 42 may be in the range of 2°(e.g., generally parallel to the longitudinal axis 42) to 90° (e.g.,generally orthogonal to the longitudinal axis 42). In some cases, thefree end 35 of the barbs 34 may angle towards the distal end 16 of thestent 10. In other cases, the barbs 34 may angle towards the proximalend 14 of the stent 10. It is further contemplated that on the samestent 10, the free end 35 of one or more of the barbs 34 (i.e., a firstsubset of barbs 34) may be angled towards the distal end 16 and the freeend 35 of one or more other barbs 34 (i.e., a second subset of barbs 34)may be angled towards the proximal end 14, as desired. In someinstances, the barbs 34 may be angled such that the free end 35 isdirected towards or pointed in the direction of likely migration. In thecase of an esophageal stent, the free end 35 of the barbs 34 may bepointed toward the distal end 16 of the stent 10 to be directed towardsthe stomach upon implantation in the esophagus.

The barbs 34 may be attached to the filaments 36 at a base or attachmentend 37 by welding, gluing, wrapping, or by other suitable methods. Inother embodiments, the barbs 34 may be formed as a unitary portion offilaments 36 with the free end 35 extending from the filament 36. Insome embodiments, the barbs 34 may be attached to the filaments 36 at oradjacent to the cross points 44 where a filament portion extending in afirst helical direction crosses a filament portion extending in a secondhelical direction, opposite the first helical direction. In otherembodiments, the barbs 34 may be attached to the filaments 36 at a pointintermediate to two cross-points 44. It is further contemplated that thestent 10 may include a plurality of barbs 34 attached at a variety ofdifferent locations relative to the cross-points 44. In other words, allof the barbs 34 need not all be attached at similar locations (e.g., allon cross-points 44 or all intermediate to two adjacent cross-points 44).

In some cases, the barbs 34 may be positioned on the stent 10 in apredetermined pattern or arrangement. The barbs 34 may be positionedalong a length of the stent 10 and/or about the circumference of stent10, as desired. It is contemplated that the barbs 34 may be positionedin any number of symmetric or asymmetric configurations along the lengthand/or circumference of the stent 10. FIG. 1 shows one illustrativeexample in which the barbs 34 are relatively evenly spaced along alength and circumference of the stent 10. In some cases, the barbs 34may be positioned over only a portion of the length (and/orcircumference) of the stent 10. For example, in some cases, the barbs 34may be positioned on only the intermediate region 18, one or both of theend regions 20, 22, or various combinations thereof. It is furthercontemplated that the barbs 34 may vary in length, as will be describedin more detail below.

The barbs 34 may be formed from a superelastic or pseudo-elasticmaterial (such as, but not limited to, Nitinol) of sufficient strengthto allow the barbs 34 to interact with body lumen tissue withoutbecoming deformed. In some cases, the barbs 34 may be formed of a shapememory material (such as, but not limited to, Nitinol) to provide thebarbs 34 with shape memory properties. Other suitable materials mayinclude polymers, metals, ceramics, composites, and/or combinationsthereof. In some cases, the barbs 34 may be formed from a materialcombination which behaves like a temperature sensitive bimetallic strip.In some cases, the barbs 34 may include a first metal and a secondmetal, wherein the first metal has a different coefficient of thermalexpansion than that of the second metal. This may cause outwardprotrusion (e.g., radial extension) of the barbs 34 from the stent 10when the barbs 34 are in contact with body temperature tissue but allowthe barbs 34 to remain straight or in a radially contracted state atroom temperature. This may allow loading and deployment interaction witha sheath or other delivery device.

The barbs 34 may be formed such that they are biased or predisposed to adeployment configuration in which the barbs 34 angle radially outwardaway from the outer surface of the elongated tubular member 12. In otherwords, the “remembered” shape or orientation of the barbs 34 may beradially extending outward from the body 12 of the stent 10. However,this orientation of the barbs 34 may cause the barbs 34 to adverselyinteract with a sheathed delivery system causing the potential fordevice malfunction. Thus, it is contemplated that the braided, knittedor woven structure of the stent 10 may be used to retain the barbs 34 ina delivery configuration to minimize or prevent the barbs 34 fromadversely interacting with the sheathed delivery system. For example,the barbs 34 may be connected to the filaments 36 at intermittent pointsaround the length and/or circumference of the stent 10. The barbs 34 maybe oriented such that their deployment configuration has them protrudingradially outward from the stent body 12, as shown in FIG. 1. Prior toloading the stent 10 in a sheath of a delivery system, the barbs 34 maybe tucked under an adjacent filament 36 (e.g., biased or temporarilydeformed) as described in more detail with respect to FIGS. 2-4. In somecases, the adjacent filament 36 may be located on the opposite side ofthe stent cell to which the barb 34 is attached and extend generallyparallel to the filament 36 which the barb 34 is attached to, or theadjacent filament 36 may be the filament crossing across (e.g., over orunder) the filament 36 which the barb 34 is attached to.

FIG. 2 illustrates a side view of a portion of an illustrative stent100, similar to the stent 10, in a collapsed configuration. The stent100 may include a stent body 112 and be similar in form and function tothe stent 10 described herein. The stent 100 may have a woven or braidedstructure, fabricated from a number of filaments or struts 136. Thefilaments 136 may form a plurality of generally diamond shaped cells 152therebetween. However, other cell 152 shapes are contemplated. The cells152 are openings or interstices extending through the stent body 112having a perimeter defined by the struts of filaments 136. In thecollapsed configuration, the major axis of the cell 152 may extend inthe longitudinal direction, as shown at arrow 150. To collapse the stent100 for delivery the stent 100 may be stretched (longitudinally 150) andcompressed (radially 160) causing elongation of the cells 152 in thelongitudinal direction 150 and contraction of the cells 152 in thecircumferential direction. As the stent 100 is moved between thecollapsed configuration (FIG. 2) and an expanded configuration (FIGS. 3and 4), such as during deployment of the stent 100, the shape of thecell 152 may change such that the cell 152 is elongated in thecircumferential direction, as shown at arrow 160 and contracted in thelongitudinal direction 150.

The stent 100 may include a plurality of retention features or barbs 134a, 134 b, 134 c (collectively, 134) (e.g., tines, quills, or barbs)attached to one or more of the filaments 136. The barbs 134 may besimilar in form and function to the barbs 34 described herein. The barbs134 a, 134 b, 134 c may be attached to a filament 136 at a first end 137a, 137 b, 137 c (collectively, 137) and extend towards a second, freeend 135 a, 135 b, 135 c (collectively, 135). In some instances, thebarbs 134 may vary in length. For example, the illustrative stent 100includes two barbs 134 a, 134 b, each having a similar first length,affixed to a first filament 136 a and a third barb 134 c having a secondlength affixed to another filament 136 d. The second length may begreater than the first length. This is just an example. The stent 100may include any number of barbs 134 having any combination of lengthsthereof. In the illustrative embodiment of FIG. 2, the free ends 135 ofthe barbs 134 all point in the same direction. This is not required. Thefree ends 135 of the barbs 134 may point in direction desired. Further,all of the barbs 134 need not be affixed to filaments 136 wound in thesame helical direction.

The barbs 134 may be affixed to the filaments 136 at locationsintermediate to the filament cross-points 144, although this is notrequired. As described herein, when the barbs 134 are attached to thestent 100, they may be biased or predisposed to extend radially outwardfrom the stent body 112 when unconstrained. To protect the deliverysystem from damage from the barbs 134, the free ends 135 of the barbs134 may be tucked or secured under an adjacent filament 136, as shown inFIG. 2, such that they do not protrude radially outward beyond the outersurface of the tubular body of the stent 10. The barbs 134 may beinitially tucked when the stent 100 is in its deployed state and thecells 152 are at their minimum radial dimension 160 and/or maximumlongitudinal dimension 150. The stent 100 may be gradually sheathed (andhence elongated and radially compressed) as the barbs 134 aresimultaneously tucked, such that the barbs 134 systematically becometrapped radially inside (e.g., under) the filaments 136 of the stent 100as the cell 152 changes shape (e.g., reduces in the radial dimension 160and elongates in the longitudinal direction 150). While the generalshape of the cell 152 remains the same in the collapsed and the expandedconfigurations (e.g., the cell 152 remains a diamond), the dimensions,area and/or angles of the cell 152 may change resulting in what isreferred to herein as a shape or profile change. For example, the angle(e.g., braid angle) at the cross-over points between intersectingfilaments may increase as the stent 100 expands from the collapsedconfiguration (FIG. 2) to the expanded configuration (FIGS. 3 and 4). Asused herein, “braid angle” is intended to mean the angle between twointerwoven filaments 136 or filament portions extending in oppositehelical directions at a cross-over point along the longitudinal axis ofthe stent 100.

The stent 100, including the tucked barbs 134 (as shown in FIG. 2), mayallow for a stent 100 with anchoring features to be delivered at ananatomical location in such a manner that the barbs 134 do not interactwith the sheath of the delivery system or protrude outward beyond theouter surface of the tubular body 112 of the stent 100 formed by theinterwoven filament(s). The barbs 134 may only become active (e.g.,extend radially from the body 112 of the stent 100) when the stent 100is unsheathed. The act of unsheathing changes the cell shapes 152 of thestent 100 (e.g., changes the area of the cells 152 and/or the anglesbetween intersecting filaments or filament portions) and allows thetrapped barbs 134 to be released and interact with the body lumen wallat the deployed location. As shown in FIG. 2, the filaments 136 may bearranged at a first braid angle θ₁ in a delivery or collapsedconfiguration.

A first barb 134 a may be affixed to a filament 136 a wound in a firsthelical direction. In a delivery or collapsed configuration, the firstbarb 134 a may be tucked underneath an adjacent filament 136 b (e.g., anadjacent filament crossing across or intersecting the filament 136 a).In other words, the first barb 134 a may be disposed radially inwards ofthe adjacent filament 136 b. In some cases, the adjacent filament 136 bmay be wound in a second helical direction, generally opposite to thefirst helical direction of the filament 136 a to which the first barb134 a is attached and intersect the first filament 136 a.

A second barb 134 b may be affixed to a filament 136 a wound in a firsthelical direction. While the second barb 134 b is illustrated as affixedto the same filament 136 a as the first barb 134 a, the second barb 134b may be affixed to any filament 136 desired. In a delivery or collapsedconfiguration, the second barb 134 b may be tucked underneath anadjacent filament 136 c (e.g., an adjacent filament crossing across orintersecting the filament 136 a). In other words, the first barb 134 amay be disposed radially inwards of the adjacent filament 136 c. As thesecond barb 134 b is circumferentially and/or longitudinally offset fromthe first barb 134 a, the second barb 134 b may be secured under adifferent filament 136 c from the first barb 134 a (which is securedunder filament 136 b). In some cases, the adjacent filament 136 b may bewound in a second helical direction, generally opposite to the firsthelical direction of the filament 136 a to which the second barb 134 bis attached and intersect the first filament 136 a.

A third barb 134 c may be affixed to a filament 136 d wound in a firsthelical direction, which may be parallel to the filament 136 a. In adelivery or collapsed configuration, the third barb 134 c may be tuckedunderneath an adjacent filament 136 c and another filament 136 e due toits length. In other words, the third barb 134 c may be disposedradially inwards of the adjacent filaments 136 c, 136 e. In some cases,the adjacent filament 136 c may be wound in a second helical direction,generally opposite to the first helical direction of the filament 136 dto which the third barb 134 c is attached. The other filament 136 eunder which the third barb 134 c is tucked may be wound in the samehelical direction as the filament 136 d and extend generally parallel tothe filament 136 d to which the third barb 134 c is attached.

It is contemplated that barbs 134 having varying lengths may be providedon the same stent 100 such that the amount of anchoring support can varywith the anatomical region being stented. For example, if the stent 100is deployed into a region of small relative diameter (compared the fullyexpanded stent 100) the braid cell profile 152 alters only slightly andpotentially only shorter barbs may be released. The stent 100 in thisorientation would have a relatively high radial force (as it is notfully deployed). This, coupled with the shorter barbs 134 a, 134 b, maybe sufficient to avoid and/or minimize migration of the stent 100.Alternatively, if the stent 100 is deployed into a region of largerelative diameter (e.g., similar to the diameter of the fully expandedstent 100) the braid cell profile 152 may alter significantly andpotentially short to medium to large barbs 134 may be progressivelyreleased. The stent 100 in this orientation would have a relatively lowradial force (as it is fully deployed). This, coupled with a longer barb136 c array may be sufficient to avoid and/or minimize migration of thestent 100. In some instances, the length of the barbs 134 may be in therange of 1.5 millimeters to 5.5 millimeters (mm). A relatively shortlength barb 134 may have a length in the range of 1.5 to 2.5 mm, amedium length barb 134 may have a length in the range of 2.5 to 3.5 mm,and a long length barb 134 may have a length in the range of 3.5 to 5.5mm, for example. These are just examples. The length of the barb 134 maybe determined by the contracted and expanded dimensions of the cell 152and/or the size of the stent 100 and can be shorter than 1.5 mm orgreater than 5.5 mm, as desired.

In some cases, the stent 100 may be centered adjacent to a tumor oranother anatomical region that has diametrical variations over a lengthof the stent 100. Various anatomical structures (such as, but notlimited to, a tumor) may result in the stent 100 assuming (at leastinitially) a dog boned shape (or a shape similar to the stent 10illustrated in FIG. 1), a tapered shape, or other shape having varyingdiameters (and/or varying degrees of stent deployment). In the case of adog-boned shape, it may be desirable to deploy shorter barbs 134 in anintermediate region where there is a greater radial force applied(because the stent 100 is not fully deployed) to the vessel by the stent100 and longer barbs 134 adjacent the end regions where the radial forceapplied to the vessel by the stent 100 may be less than the intermediateregion. It is contemplated that longer barbs 134 may extend farther intothe tissue and provide more anchoring (or anti-migration support) thanshorter barbs 134. It is further contemplated that including barbs 134of varying length may also be used in stents 100 where the shape of thestent 100 may vary over time. For example, in long term implants, thediameter of the stent 100 may change (e.g., increase) over time.Additional anchoring may be required as the diameter increases and lessradial force is applied to the vessel wall by the stent 100. In such aninstance, the inclusion of longer or varying length barbs 134 that canbe deployed over time as the diameter of the stent 100 increases mayprovide additional anchoring over time. It is further contemplated thatthe location at which the barbs 134 are attached to the stent 100 (e.g.,distance between cross-points) may also influence when the barbs 134 aredeployed. As can be appreciated, for a barb 134 having a constantlength, the farther the barb 134 is attached from the adjacent filament,the quicker it will be deployed as the stent 100 is expanded.

FIG. 3 illustrates a side view of the illustrative stent 100 of FIG. 2in a partially deployed or expanded configuration in which the diameterof the stent has increased from the collapsed, delivery configuration.As the stent 100 radially expands and/or longitudinally contracts, theprofile of the cells 152 may change (e.g., the area and/or angles of thecells 152 may change). For example, the filaments 136 may be arranged ata second braid angle θ₂ in the partially deployed or expandedconfiguration. The second braid angle θ₂ may be greater than the firstbraid angle θ₁. Furthermore, the area of the cells 152 may increase froman area of the cells 152 in the delivery or collapsed configuration tothe partially deployed or expanded configuration. As can be seen in FIG.3, the shorter barbs 134 a, 134 b have been released from under adjacentfilaments 136 b, 136 c and deployed and the free ends 135 a, 135 b arenow extending radially outward from the outer surface of the body 112 ofthe stent 100 while the free end 135 c of the longer barb 134 c is stillsecured under an adjacent filament 136 c.

Further deployment of the stent 100 (e.g., further radial expansionand/or longitudinal contraction of the stent 100), as shown in FIG. 4,further changes the profile of the cells 152 (e.g., further increasesarea and/or angles of the cells 152) which may release the longer barb134 c from under adjacent filament 136 c such that the barb 134 c alsoextends radially outward from the outer surface of the body 112 of thestent 100. For example, the filaments 136 may be arranged at a thirdbraid angle θ₃ in the fully deployed or expanded configuration. Thethird braid angle θ₃ may be greater than the first braid angle θ₁ andthe second braid angle θ₂. Furthermore, the area of the cells 152 mayincrease from the area of the cells 152 in the delivery or collapsedconfiguration as well as the partially deployed or expandedconfiguration. Thus, the area of the cells 152 in the fully deployed orexpanded configuration may be greater than the area of the cells 152 inthe delivery or collapsed configuration and/or the partially deployed orexpanded configuration.

FIG. 5 illustrates a perspective view of another illustrative stent 200in an expanded (e.g., deployed) configuration. The stent 200 may includea tubular stent body extending along a longitudinal axis 250 and besimilar in form and function the stent 10 described herein. The stent200 may have a woven or braided structure, fabricated from a number ofinterwoven filaments or struts 236. The filaments 136 may form aplurality of generally diamond shaped cells 252. However, other cell 252shapes are contemplated. The stent 200 may include a plurality ofretention features 234 (e.g., tines, quills, or barbs) attached to oneor more of the filaments 236. The barbs 234 may be similar in form andfunction to the barbs 34, 134 described herein.

As can be seen in FIG. 5, the barbs 234 may extend radially outward froman outer surface of the stent 200. While FIGS. 2-4 illustrate the barbs134 as being attached at a terminal end of the barb 134 to the stent100, FIG. 5 illustrates the barbs 234 can be affixed to the stent 200along a portion of the length of the barb 234. Securing the barbs 234along a length (as opposed to securing at an end point) may provide amore rigorous means of attachment. In some cases, the barbs 234 may besecured along a length 270 approximately equivalent to a length betweentwo adjacent cross-points 244. This is just an example.

FIG. 6 illustrates a side view of another illustrative stent 300 in acollapsed configuration within a delivery sheath 302. The stent 300 mayinclude a tubular stent body 312 and be similar in form and function tothe stent 10 described herein. The stent 300 may have a woven or braidedstructure, fabricated from a number of filaments or struts 336. Thestent 300 may include a plurality of retention features 334 (e.g.,tines, quills, or barbs) attached to one or more of the filaments 336.The barbs 334 may be similar in form and function to the barbs 34, 134,234 described herein. In some instances, the barbs 334 may include morethan one barb 334 attached at the same location, as shown in FIG. 6.

In some embodiments, the barbs 334 may be concentrated adjacent to aproximal end 314 of the stent 300. Alternatively, or additionally, thebarbs 334 may be concentrated adjacent to a distal end (not explicitlyshown) of the stent 300. The barbs 334 may be retained in a collapsedconfiguration by the delivery sheath 302. Once the target vessel hasbeen reached, the sheath 302 may be proximally retracted, as shown atarrow 350. Once the sheath 302 has been removed from the regionincluding the barbs 334, as shown in FIG. 7, the barbs 334 may bedeployed such that they extend radially from the body 312 of the stent300 to engage the tissue. In some instances, a portion of the stent 300,such as the distal end portion (not shown) opposite the end includingthe barbs 334 may be deployed and expanded in the body lumen prior toremoving the sheath 302 to deploy the barbs 334 at the proximal end 314of the stent 300. While FIGS. 6 and 7 illustrate two circumferentialgroups or banks of barbs 334, it is contemplated that the to stent 300may include only a single bank of barbs 334 or more than two banks ofbarbs 334, as desired. Further the groups of barbs 334 need not bearranged circumferentially about the stent 300. As described above, thebarbs 334 may be oriented in any longitudinal and/or circumferentialarrangement desired.

FIG. 8 illustrates a side view of another illustrative stent 400 in acollapsed configuration. FIG. 9 illustrates a side view of theillustrative stent 400 of FIG. 8 in a radially expanded configuration.The stent 400 may include a tubular stent body 412 and be similar inform and function to the stent 10 described herein. The body 412 of thestent 400 may have a woven or braided structure, fabricated from anumber of interwoven filaments or struts 436 defining cells 452therebetween. The stent 400 may include a plurality of retentionfeatures 434 (e.g., tines, quills, or barbs) attached to one or more ofthe filaments 436. The barbs 434 may be similar in form and function tothe barbs 34, 134, 234, 334 described herein. In some cases, the barbs434 may be formed from a filament or wire. Both ends 439 a, 439 b of thefilament or wire of the barb 434 may be affixed to the filament 436. Thebarbs 434 may form a generally pointed or triangular shape with thefilaments 436. However, other shapes are also contemplated. A regionintermediate to the ends 439 a, 439 b may from the free end or portion435 which may be configured to engage bodily tissue.

The barbs 434 may be attached to the stent 400 such that they may bebiased or predisposed to extend radially outward from the outer surfaceof the stent body 412. To protect the delivery system from damage fromthe barbs 434, the free end 435 of the barbs 434 may be tucked orsecured under an adjacent filament 436 (i.e., radially inward of theadjacent filament 436), as shown in FIG. 8, such that the barbs 434 donot protrude radially out beyond the outer surface of the body 412. Asthe stent 400 is radially expanded, the barbs 434 may becomeunconstrained from the adjacent filament 436 and rotate 430 such thatthe free end 435 extends radially outward beyond the body portion 412 ofthe stent 400, as shown in FIG. 9. The spaced apart ends 439 a, 439 bmay allow the barbs 434 to function as a hinge or spring mechanism. Forexample, the protrusion angle of barbs 434 may be varied (e.g.,increased or decreased) if acute repositioning or removal of the stent400 is required. In some cases, with the correct placement on thefilament 436, the barbs 434 may be retrapped under the filaments (asshown in FIG. 8) to facilitate removal and or repositioning of the stent400.

FIG. 10 illustrates a side view of another illustrative stent 500 in acollapsed configuration. FIG. 11 illustrates a side view of theillustrative stent 500 of FIG. 10 in a radially expanded configuration.The stent 500 may include a tubular stent body 512 and be similar inform and function to the stent 10 described herein. The body 512 of thestent 500 may have a woven or braided structure, fabricated from anumber of interwoven filaments or struts 536 defining cells 552therebetween. The stent 500 may include a plurality of retentionfeatures 534 (e.g., tines, quills, or barbs) attached to one or more ofthe filaments 536. The barbs 534 may be similar in form and function tothe barbs 34, 134, 234, 334, 434 described herein. In some cases, thebarbs 534 may be formed from a filament or wire having a coiled portion540 (see FIG. 10A) wrapped or wound around one of the filaments 536,such as a first filament 536 a. The coiled portion 540 may be welded orotherwise affixed to the filament 536 a in some instances. The filamentforming the barb 534 may include a first end portion 538 a extendingfrom the coiled or base portion 540 to a first tip or free end 535 aand/or a second end portion 538 b extending from the coiled or baseportion 540 to a second tip or free end 535 b.

The barbs 534 may be attached to the stent 500 such that they may bebiased or predisposed to extend radially outward from the outer surfaceof the stent body 512. To protect the delivery system from damage fromthe barbs 534, the free end(s) 535 a/535 b of the barbs 534 may betucked or secured under an adjacent filament 436 (i.e., radially inwardof the adjacent filament 536), as shown in FIG. 10, such that the barbs534 do not protrude radially out beyond the outer surface of the body512. For example, as shown in the cross-section of FIG. 10A, the firstfree end 535 a may be arranged radially inward of a second filament 536b and the second free end 535 b may be arranged radially inward of athird filament 536 c, such that the filaments 535 b/535 c restrain thefree ends 535 a/535 b from extending radially outward of the outersurface of the stent body 512.

As the stent 500 is radially expanded, the free ends 535 a/535 b of thebarbs 534 may become unconstrained from the adjacent filaments 536 b/536c and spring radially outward such that the free ends 535 a/535 b extendradially outward beyond the body portion 512 of the stent 500, as shownin FIGS. 11 and 11A.

As the stent 500 radially expands from the delivery or radiallycollapsed configuration in FIGS. 10 and 10A to the radially expandedconfiguration in FIGS. 11 and 11A, the profile of the cells 552 maychange (e.g., the area and/or angles of the cells 552 may change). Forexample, as discussed above, the filaments 536 may be arranged at afirst braid angle in the radially collapsed configuration and a secondbraid angle, greater than the first braid angle, in the radiallyexpanded configuration. Additionally, the area of the cells 552 mayincrease from an area of the cells 552 in the radially collapsedconfiguration to the radially expanded configuration. Furthermore, asshown in FIGS. 10A and 10B, the distance between the attachment point(e.g., the coil or base portion 540 on the first filament 536 a to theadjacent filaments 536 b/536 c may change as the stent 500 is radiallyexpanded. For example, the distance between the attachment point (e.g.,the coil or base portion 540 on the first filament 536 a to the point ofthe adjacent filaments 536 b/536 c under which the free ends 535 a/535 bare positioned may be a first distance D₁ in the radially collapsedconfiguration (FIG. 10A) and the distance between the attachment point(e.g., the coil or base portion 540) on the first filament 536 a to thepoint of the adjacent filaments 536 b/536 c under which the free ends535 a/535 b were positioned may be a second distance D₂ in the radiallyexpanded configuration (FIG. 11A). The second distance D₂, which may begreater than the first distance D₁, may be large enough to allow thefree ends 535 a/535 b to clear the filaments 536 b/536 c and deflectradially outward of the outer surface of the body 512 of the stent 500.In other words, the first distance D₁ may be less than the length of thebarb 534 from the base or coiled portion 540 to the free end 535 whereasthe second distance D₂ may be greater than the length of the barb 534from the base or coiled portion 540 to the free end 535.

The stents, delivery systems, and the various components thereof, may bemade from a metal, metal alloy, polymer (some examples of which aredisclosed below), a metal-polymer composite, ceramics, combinationsthereof, and the like, or other suitable material. Some examples ofsuitable metals and metal alloys include stainless steel, such as 304V,304L, and 316LV stainless steel; mild steel; nickel-titanium alloy suchas linear-elastic and/or super-elastic nitinol; other nickel alloys suchas nickel-chromium-molybdenum alloys, nickel-copper alloys,nickel-cobalt-chromium-molybdenum alloys, nickel-molybdenum alloys,other nickel-chromium alloys, other nickel-molybdenum alloys, othernickel-cobalt alloys, other nickel-iron alloys, other nickel-copperalloys, other nickel-tungsten or tungsten alloys, and the like;cobalt-chromium alloys; cobalt-chromium-molybdenum alloys; platinumenriched stainless steel; titanium; combinations thereof; and the like;or any other suitable material.

Some examples of suitable polymers for the stents or delivery systemsmay include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene(ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, forexample, DELRIN® available from DuPont), polyether block ester,polyurethane (for example, Polyurethane 85A), polypropylene (PP),polyvinylchloride (PVC), polyether-ester (for example, ARNITEL®available from DSM Engineering Plastics), ether or ester basedcopolymers (for example, butylene/poly(alkylene ether) phthalate and/orother polyester elastomers such as HYTREL® available from DuPont),polyamide (for example, DURETHAN® available from Bayer or CRISTAMID®available from Elf Atochem), elastomeric polyamides, blockpolyamide/ethers, polyether block amide (PEBA, for example availableunder the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA),silicones, polyethylene (PE), Marlex high-density polyethylene, Marlexlow-density polyethylene, linear low density polyethylene (for exampleREXELL®), polyester, polybutylene terephthalate (PBT), polyethyleneterephthalate (PET), polytrimethylene terephthalate, polyethylenenaphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI),polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide(PPO), poly paraphenylene terephthalamide (for example, KEVLAR®),polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMSAmerican Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinylalcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC),poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS50A), polycarbonates, ionomers, biocompatible polymers, other suitablematerials, or mixtures, combinations, copolymers thereof, polymer/metalcomposites, and the like.

In at least some embodiments, portions or all of the stents or deliverysystems may also be doped with, made of, or otherwise include aradiopaque material. Radiopaque materials are generally understood to bematerials which are opaque to RF energy in the wavelength range spanningx-ray to gamma-ray (at thicknesses of <0.005″). These materials arecapable of producing a relatively dark image on a fluoroscopy screenrelative to the light image that non-radiopaque materials such as tissueproduce. This relatively bright image aids the user of the stents ordelivery systems in determining its location. Some examples ofradiopaque materials can include, but are not limited to, gold,platinum, palladium, tantalum, tungsten alloy, polymer material loadedwith a radiopaque filler, and the like. Additionally, other radiopaquemarker bands and/or coils may also be incorporated into the design ofthe stents or delivery systems to achieve the same result.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps without exceeding the scope of thedisclosure. This may include, to the extent that it is appropriate, theuse of any of the features of one example embodiment being used in otherembodiments. The invention's scope is, of course, defined in thelanguage in which the appended claims are expressed.

What is claimed is:
 1. A stent, the stent comprising: an elongatedtubular member comprising at least one filament wound to form aplurality of cells, the elongated tubular member configured to movebetween a collapsed configuration and an expanded configuration, whereinin the collapsed configuration the plurality of cells have a firstprofile and in the expanded configuration the plurality of cells have asecond profile different from the first profile; and at least one barbattached to the at least one filament at one end of the barb andextending towards a free end; wherein the free end of the at least onebarb is configured to be positioned radially inward to an adjacentwinding of the at least one filament when the elongated tubular memberis in the collapsed configuration and to extend radially away from theelongated tubular member when the elongated tubular member is in theexpanded configuration.
 2. The stent of claim 1, wherein the firstprofile of the plurality of cells has a major dimension extending alonga longitudinal axis of the elongated tubular member.
 3. The stent ofclaim 1, wherein the second profile of the plurality of cells has amajor dimension extending along a circumference of the elongated tubularmember.
 4. The stent of claim 1, wherein the at least one barb comprisesa wire.
 5. The stent of claim 4, wherein the at least one barb isattached to the at least one filament at a terminal end of the at leastone barb.
 6. The stent of claim 4, wherein the at least one barb isattached to the at least one filament along a length of the at least onebarb, the length extending from a terminal end to a point proximal tothe free end.
 7. The stent of claim 4, wherein the at least one barb isattached to the at least one filament at a first end of the at least onebarb and a second end of the at least one barb, wherein the free end ofthe at least one barb is a region intermediate to the first end and thesecond end.
 8. The stent of claim 7, wherein the at least one barb has agenerally triangular shape.
 9. The stent of claim 1, wherein the atleast one barb comprises a wire helically wound around the at least onefilament.
 10. The stent of claim 9, wherein the at least one barb isbiased to extend radially outward from the elongated tubular member whenunconstrained.
 11. The stent of claim 1, wherein the at least one barbcomprises a material combination which behaves like a temperaturesensitive bimetallic strip.
 12. The stent of claim 1, wherein the atleast one barb comprises a plurality of barbs spaced along a length anda circumference of the elongated tubular member.
 13. The stent of claim1, wherein the at least one barb comprises a plurality of barbs, whereinat least some of the plurality of barbs have a first length and at leastsome of the plurality of barbs have a second length different from thefirst length.
 14. The stent of claim 1, wherein the at least one barbcomprises two or more wires fixed at a same location on the at least onefilament.
 15. A stent, the stent comprising: an elongated tubular membercomprising at least one filament wound to form a plurality of cells, theelongated tubular member configured to move between a collapsedconfiguration and an expanded configuration; and a plurality of barbsaffixed to the at least one filament and comprising a shape memory wire,the plurality of barbs biased to extend radially outward from theelongated tubular member when unconstrained; wherein in the collapsedconfiguration the ate least one filament applies a radially inwardconstraining force to a free end of each barb of the plurality of barbssuch that the free ends are constrained radially inward of the at leastone filament and as the elongated tubular member moves from thecollapsed configuration to the expanded configuration the free end of atleast some of the plurality of barbs is unconstrained by the at leastone filament and extends radially outward from the elongated tubularmember.
 16. The stent of claim 15, wherein at least some of theplurality of barbs have a first length and at least some of theplurality of barbs have a second length greater than the first length.17. The stent of claim 16, wherein the constraining force is removedfrom the barbs having the first length before the barbs having thesecond length.
 18. A stent, the stent comprising: an elongated tubularmember comprising at least one filament wound to form a plurality ofcells, the elongated tubular member configured to move between acollapsed configuration and an expanded configuration, wherein in thecollapsed configuration the plurality of cells have a first profile andin the expanded configuration the plurality of cells have a secondprofile different from the first profile; and at least one barb attachedto the at least one filament at one end of the barb and extendingtowards a free end; wherein the first profile is configured to exert aconstraining force on the at least one barb to position the at least onebarb radially inward of the at least one filament and the second profileis configured to remove the constraining force from the at least onebarb such that the free end of the at least one barb extends radiallyoutward from the elongated tubular member.
 19. The stent of claim 18,wherein the at least one barb comprises a shape memory material.
 20. Thestent of claim 18, wherein when the free end of the at least one barbextends radially outward from the elongated tubular member, the at leastone barb is at an angle of in the range of 2° to 90° relative to alongitudinal axis of the elongated tubular member.